PlaitToML

The following is a compiler which translates a subset of the Plait language into OCaml.

Plait is a statically typed language that syntatically resembles Racket, but has a type system similar to ML. For this reason, I decided to implement a compiler which translates between the two languages languages. I mostly just included features of the Plait language that I use. Other features could definitely be added in the future.

The following features of Plait were not included for simplicity reasons, but I hope to include them in the future:

• some definition and lambda forms with explicit type declarations
  • Example 1: (define x : Number 10)
  • Example 2: (lambda (x) : Number (+ x 10))
• (cond ...), (begin ...), (set! ...), and (try ...)
• (values ...) form
• macros
• modules
• trace function
• ... placeholder, for ex: (if #f ... 'ok)
• vector and box
• quasiquote and unquote
• (#%app ...)
• (case ...), since type-case is much more prevalent in Plait
• (when ...) and (unless ...)
• (local ...)
• (shared ...)
• (parameterize ...)
• (time ...)
• (let/cc ...) and (call/cc ...)
• Many primops are not supported yet, but can be easily implemented.
• tuple arguments (however, curried arguments and function arguments are supported)
• untyped, lazy, and fuel modes

Limits of the nanopass parser resulted in the following forms not being included. I haven't looked into a solution for this yet, but it would be nice to allow for the else keyword in a type-case and conditional branch.

• else case of a type-case
• else case of a cond

Directory Structure

• main.rkt
  • Entry point to the compiler. Takes in a plait file and compiles it into ML.
• plait.rkt
  • Nanopass language definition for Plait.
• simplify.rkt
  • Conversion passes that run before codegen. Includes the following:
    • Let to λ conversion
    • Unroll let* and letrec
    • Remove type declarations
    • Obey OCaml capitalization and naming conventions
    • Compile away plait accessor/predicate functions into ML match expressions.
• codegen.rkt
  • Compiles the Plait IR into an ML code string.